Battery cell mechanical safety coupling evaluation method and testing device

Abstract

The invention discloses a battery cell mechanical safety coupling evaluation method and a testing device. The method comprises the steps that under different testing conditions, an impact body is used for conducting impact testing on a battery cell, and the impact body is provided with a structure used for generating an extrusion effect and a needling effect at the same time during impact; acquiring voltage data, temperature data and appearance state of the battery cell in each impact test, and the impact speed of an impact body; calculating impact energy based on the mass of the impact body and the impact speed; evaluating the safety performance of the battery cell based on the voltage data, the temperature data, the appearance state and the impact energy under different test conditions; and through the extrusion evaluation model and the acupuncture evaluation model, respectively quantifying the severity of the extrusion effect and the acupuncture effect in the impact body so as to analyze the dominant mode in the mechanical damage. According to the invention, synchronous simulation, quantitative evaluation and analysis of the influence of extrusion and acupuncture coupling damage on the safety of the battery cell can be realized, and the authenticity of the test and the comprehensiveness of evaluation are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of battery cell safety testing technology, and more specifically, relates to a battery cell mechanical safety coupling assessment method and testing device. Background Technology

[0002] As the core energy storage unit of lithium-ion power batteries, the mechanical safety of the battery cell is a key factor affecting the overall safety and reliability of electric vehicles, energy storage systems, and other applications. In actual use, battery cells may be subjected to complex mechanical loads due to unexpected events such as vehicle collisions, battery pack drops, and foreign object impacts, leading to damage to their internal structure and potentially causing serious safety accidents such as internal short circuits, thermal runaway, or even fires and explosions. Therefore, establishing scientific and effective mechanical safety assessment methods is of great significance for the design optimization, quality control, and safety standard formulation of battery cell products.

[0003] Currently, the industry's standardized testing methods for the mechanical safety of battery cells mainly focus on two single mechanical abuse scenarios: crush test and needle penetration test.

[0004] Extrusion tests typically simulate static or quasi-static mechanical loads. This test involves slowly applying extrusion force to the battery cell and observing its physical deformation, the occurrence of internal short circuits, and whether thermal runaway is triggered. However, this method suffers from low loading rates and long durations, making it unable to accurately reproduce the instantaneous, high-energy impact events common in real-world collision accidents. The test results primarily reflect the safety of the battery cell under slow deformation, but fail to effectively capture key mechanisms such as the dynamic response under impact loads and the "impact heat" caused by instantaneous energy injection. Furthermore, the test scenario differs significantly from real-world high-momentum collision conditions.

[0005] The needle penetration test primarily simulates the extreme scenario of a sharp foreign object piercing the battery cell's separator. This test uses a steel needle to pierce the cell at a constant speed, artificially triggering an internal short circuit and observing thermal runaway behavior. While this method is directly effective in triggering internal short circuits, its mechanical triggering mode is too simplistic and specific, representing only a sharp, localized puncture damage. In real-world complex accidents (such as side impacts or undercarriage scrapes), battery cells more commonly suffer from coupled damage caused by blunt objects or structural components, including large-area compression, wrinkling, tearing, and accompanying localized punctures. A single sharp needle penetration cannot characterize this more general, complex failure mode caused by blunt impact.

[0006] In summary, existing standardized testing methods (extrusion and puncture) consider these two basic mechanical damage modes in isolation. However, under real-world mechanical abuse conditions, cell damage is often the result of multiple modes acting together and coupling with each other. This coupling can significantly alter the cell's failure threshold, thermal triggering sensitivity, and severity. Current isolated testing systems struggle to simulate and evaluate these coupled damage effects, resulting in insufficient disclosure of cell safety risks under complex real-world conditions and failing to provide comprehensive and accurate input for the mechanical safety design of cells.

[0007] Therefore, the industry urgently needs a new method and corresponding device that can simulate and quantify the safety performance of battery cells under the coupling of extrusion and puncture, in order to fill the gap in the existing testing system in simulating real complex mechanical abuse scenarios and improve the engineering relevance of test results and the accuracy of safety warnings. Summary of the Invention

[0008] The purpose of this invention is to propose a method and testing device for evaluating the mechanical safety coupling of battery cells, which solves the key technical problem that traditional battery cell mechanical safety testing methods isolate extrusion and puncture damage and cannot simulate the coupling effect between the two in real complex working conditions; it realizes synchronous simulation, quantitative evaluation and analysis of the impact of extrusion and puncture coupled damage on battery cell safety, and significantly improves the authenticity of the test and the comprehensiveness of the evaluation.

[0009] To achieve the above objectives, in a first aspect, the present invention proposes a method for evaluating the mechanical safety coupling of battery cells, comprising: Under different test conditions, the battery cell is subjected to impact test using an impactor, the impactor having a structure for generating both squeezing and needle-piercing effects during impact. Acquire the voltage data, temperature data, and appearance of the battery cell, as well as the impact velocity of the impactor, in each impact test; The impact energy is calculated based on the mass and impact velocity of the impactor. The safety performance of the battery cell is evaluated based on the voltage data, temperature data, appearance condition, and impact energy under different test conditions. By using compression assessment models and needle puncture assessment models, the severity of compression and needle puncture effects in the impactor are quantified respectively, in order to analyze the dominant mode in the mechanical damage.

[0010] Optionally, the test conditions include: The different states of charge of the battery cell, and the different impact energies obtained by adjusting the release height, release angle or mass of the impactor.

[0011] Optionally, the impact test is performed by driving the impact body in the form of free fall or a pendulum.

[0012] Optionally, the compression assessment model is used to calculate a compression assessment factor characterizing the severity of the compression effect, and its expression is: ; in, The total displacement caused by the work done by the impactor perpendicular to the surface of the battery cell is expressed as a function. Related to the size and mechanical properties of the battery cell, The upper limit of the displacement for work done. To test the mass of the impactor, For the quality of the battery cell under test, The falling height or equivalent falling height of the impactor.

[0013] Optionally, the acupuncture evaluation model is used to calculate an acupuncture evaluation factor characterizing the severity of the acupuncture effect, and its expression is: ; in, The depth to which the protruding structure penetrates the battery cell under test. The standard insertion depth for traditional needle prick tests. It is the semi-cone angle of the convex structure.

[0014] Optionally, the dominant mode of analysis of mechanical damage includes: contrast and The value; like If so, then the acupuncture factor is determined to be the dominant mode of mechanical injury; like If the compression factor is determined to be the dominant mode of mechanical damage, then the compression factor is determined to be the dominant mode.

[0015] Optionally, the impactor includes a body and at least one protrusion structure disposed on the surface of the body.

[0016] Optionally, the protruding structure is a conical structure detachably mounted on the main body, made of tungsten steel or stainless steel, with a height of 5mm to 60mm, a tip diameter of 1mm to 20mm, a tail diameter of 1mm to 50mm, and a semi-cone angle of 15° to 45°.

[0017] Optionally, the expression for calculating the impact energy is: E ; in, The mass of the impactor. The impact velocity of the impactor. , It is the acceleration due to gravity. The falling height or equivalent falling height of the impactor.

[0018] In a second aspect, the present invention provides a battery cell mechanical safety coupling testing device for implementing the battery cell mechanical safety coupling assessment method described in the first aspect, the device comprising: Fixtures used to secure battery cells; An impactor having a structure for generating both squeezing and needle-piercing effects during impact; A release mechanism is used to release the impactor so that it strikes the battery cell in the form of a free fall or a pendulum. The control module is used to control the release mechanism to release the impactor; The data acquisition unit is used to acquire the voltage data, temperature data, and appearance of the battery cell, as well as the impact velocity of the impactor. The analysis and processing unit is communicatively connected to the data acquisition unit. It is used to calculate the impact energy based on the velocity data, and to evaluate the safety performance of the battery cell based on the voltage data, temperature data, appearance condition and impact energy under different test conditions. It also uses the compression evaluation model and the needle penetration evaluation model to quantify the severity of the compression and needle penetration effects in the impact body, respectively, in order to analyze the dominant mode in the mechanical damage.

[0019] The beneficial effects of this invention are as follows: by using an impactor that simultaneously exhibits extrusion and puncture effects in the impact test, the complex mechanical damage faced by the battery cell in real-world scenarios can be reproduced, avoiding the problem of traditional single testing being disconnected from actual working conditions; at the same time, by combining multi-dimensional data (voltage, temperature, appearance) with the correlation analysis of impact energy, the safety performance boundaries of the battery cell under different test conditions can be more accurately assessed; furthermore, by using extrusion and puncture assessment models to quantify the severity of the two effects, the dominant mode of mechanical damage can be clearly identified, providing a more targeted reference for battery cell structure optimization and safety design, ultimately improving the authenticity, comprehensiveness, and guiding value of battery cell mechanical safety testing.

[0020] The system of the present invention has other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0021] The above and other objects, features and advantages of the present invention will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0022] Figure 1 A flowchart illustrating the steps of a cell mechanical safety coupling assessment method according to Embodiment 1 of the present invention is shown.

[0023] Figure 2 A schematic diagram of an impactor according to Embodiment 1 of the present invention is shown.

[0024] Figure 3 A schematic diagram of an impactor according to Embodiment 1 of the present invention is shown.

[0025] Figure 4 A schematic diagram of the protrusion structure according to Embodiment 1 of the present invention is shown.

[0026] Figure 5 A schematic diagram of a core-mechanical safety coupling test device according to Embodiment 2 of the present invention is shown.

[0027] Figure 6 A schematic diagram of a core-mechanical safety coupling test device according to Embodiment 3 of the present invention is shown. Detailed Implementation

[0028] The invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0029] Example 1

[0030] like Figure 1 As shown, this embodiment provides a method for evaluating the mechanical safety coupling of a battery cell, including: S1. Under different test conditions, the battery cell is subjected to impact test using an impactor. The impactor is equipped with a structure to generate both squeezing and needle-piercing effects during impact. Specifically, by systematically changing key test variables, the diverse operating conditions that battery cells may encounter in practical applications are simulated. These different test conditions mainly cover the internal state of the battery cell, external mechanical input, and the physical characteristics of the impactor itself. Specifically, the test needs to be conducted at different states of charge (SOC) of the battery cell (e.g., 0%, 50%, 100%) to examine the correlation between its internal chemical energy and safety risks; at the same time, by precisely adjusting the release height, release angle, or mass of the impactor, the energy level when it impacts the battery cell can be controlled, thereby simulating different impact intensities from mild to severe; in addition, the structural characteristics of the impactor, such as its main body shape, size, and the geometric parameters of surface protrusions (e.g., height, sharpness), are also important conditions that can be systematically changed to correspond to different contact forms and damage modes.

[0031] To simulate realistic and complex damage, this method employs a specially designed impactor. The core design feature of this impactor lies in its integrated composite structure that simultaneously generates both compression and puncture effects. Typically, the impactor comprises a main body (such as a spherical or cylindrical metal block) with a certain mass and stiffness. Its function is to transfer kinetic energy to the battery cell through large-area contact upon impact, producing a compression and crushing effect similar to blunt force impact. Simultaneously, at least one protruding structure (preferably a detachable "fang"-shaped cone) is provided on the surface of this main body. When the impactor strikes the battery cell, this protruding structure simultaneously pierces the battery cell casing and interior, generating localized stress concentration, simulating the puncture effect of a sharp object. Through this organic combination of "surface contact" and "point contact," a single impact event can simultaneously induce large-area plastic deformation and localized intrusive damage on the battery cell, thereby accurately reproducing the complex mechanical abuse scenario of compression and puncture coupling in reality, providing a realistic physical basis for subsequent coupling analysis.

[0032] In this step, the test conditions include: Different states of charge of the battery cell, and different impact energies obtained by adjusting the release height, release angle or mass of the impactor.

[0033] Specifically, the test conditions set in this method are the core of constructing a multi-dimensional evaluation scenario, mainly including two independent yet interconnected levels: One aspect is the internal energy state of the battery cell, namely its state of charge (SOC). At different SOCs, the activity of the internal chemical system, the energy that can be released, and the thermal stability of the battery cell vary significantly. Testing is typically conducted at key points such as 0% (empty charge, representing the lowest energy risk), 50% (medium energy state), and 100% (fully charged, representing the highest energy risk). By comparing the responses of battery cells with different SOCs under the same mechanical load (such as the rate of voltage drop, the magnitude of temperature rise, and whether thermal runaway is triggered), the decisive influence of the internal energy storage level of the battery cell on the safety boundary of mechanical abuse can be directly revealed.

[0034] The second is the external mechanical input applied to the battery cell, namely impact energy. This energy is not directly set, but is indirectly and controllably achieved by precisely adjusting the physical parameters of the impact testing device. Specifically: the adjustment of the release height and release angle corresponds to the two driving forms of free fall and pendulum, respectively, directly determining the instantaneous velocity of the impactor; while the replacement or adjustable design of the impactor's mass determines the impactor's inertia. According to the principles of physics, the impact energy (E) is given by the formula E Decision, among which For quality, At impact velocity, drag accounts for 0.16%, which is negligible. Therefore, by systematically changing the two independent variables of height (or angle) and mass, precise calibration and continuous range coverage of impact energy can be achieved, thereby simulating different impact severities from minor bumps to severe collisions. This quantitative control of input energy forms the basis for subsequent quantitative coupled analysis of mechanical damage.

[0035] In this step, the impact test is performed by driving the impactor through free fall or a pendulum.

[0036] Specifically, the mechanism for driving the impactor to complete the test is designed with two classic and controllable dynamic forms: free fall and pendulum. In the free fall form, the impactor is raised to a preset, precisely measurable vertical height and then released, allowing it to accelerate downwards along a guide rail or guide device under the influence of gravity. Its impact velocity is determined solely by the fall height and gravitational acceleration. , It is the acceleration due to gravity. The impactor's fall height (in free fall mode) or equivalent fall height (in pendulum mode) allows for predictable and reproducible control over the input energy. In the pendulum mode, the impactor is fixed to the end of the pendulum rod and released after being pulled to a preset initial angle. Driven by its gravitational potential energy, the pendulum accelerates along a circular trajectory and strikes the battery cell at its lowest point. The impact velocity is determined by the initial angle (which determines the potential energy) and the pendulum length. Both modes can convert preset height or angle parameters into repeatable, instantaneous impact velocities and energy using basic physical principles. This allows for reliable reproduction of high-energy instantaneous impact events from various directions, from vertical drops to bottom impacts, in a laboratory environment, providing a crucial technical means for simulating dynamic loads in real-world accidents.

[0037] In this step, the impactor includes a body and at least one protruding structure disposed on the surface of the body.

[0038] Specifically, the impactor consists of two key parts, forming a functionally integrated composite structure. The core part is a main body with a certain mass and rigidity, usually made of metal (such as steel or aluminum), and its shape can be designed according to testing requirements, such as spherical, cylindrical, or polygonal. The main function of this main body is to transfer kinetic energy to the battery cell through its overall mass and contact area at the moment of impact, thereby simulating the large-scale compression, crushing, or bending damage modes caused by blunt object impact. Its function is similar to that of a mass block or hammer.

[0039] To achieve more complex and realistic damage simulation, at least one protruding structure is provided on the outer surface of the main body. These protrusions are not simple rough points, but specially designed (usually conical or fang-shaped rigid tips) made of a material harder than the main body (such as tungsten steel) to ensure durability and penetration. The core function of this protruding structure is that, while the main body is subjected to large-area compression, its sharp or protruding parts can locally and concentratedly penetrate the cell casing. This simulates sharp parts that may be embedded in impacting objects, or hard points such as structural edges and bolts in real-world scenarios, thereby simultaneously triggering localized puncture, shearing, or tearing effects, i.e., needle-puncture damage.

[0040] Therefore, through this integrated "body + protrusion" design, a single impactor can simultaneously and synchronously apply two basic mechanical forces during a single impact: the distributed compressive load from the body and the concentrated puncture load from the protrusion. This accurately reproduces the complex mechanical damage commonly seen in real accidents caused by a single impact event, providing a physical basis for studying the coupling effect of the two modes of compression and puncture and their combined impact on cell safety. The number, size, shape, and distribution of the protrusion structure can all be adjusted, providing flexibility for simulating different types of threat scenarios.

[0041] In one specific embodiment, the structure of the impactor is as follows: Figure 2 and Figure 3 As shown.

[0042] In this step, the protruding structure is a conical structure that is detachably mounted on the main body. It is made of tungsten steel or stainless steel, with a height of 5mm to 60mm, a tip diameter of 1mm to 20mm, a tail diameter of 1mm to 50mm, and a semi-cone angle of 15° to 45°.

[0043] Specifically, the protrusion structure is specially designed as a detachable, rigid cone with specific geometric parameters. Its detachable connection method (e.g., by threaded insertion into the main body) provides high flexibility and economy, allowing for easy replacement of protrusions of different sizes, shapes, or materials during a single test to systematically study the impact of geometric variables on damage results without replacing the entire impactor. In terms of materials, alloys with extremely high hardness, wear resistance, and a certain degree of toughness, such as tungsten steel or stainless steel, are selected to ensure that it is not easily deformed or broken under high-speed impact, and can stably penetrate the battery cell casing, guaranteeing the reliability and repeatability of the test. Its geometry is carefully defined: a height range of 5 mm to 60 mm allows it to simulate both shallow surface scratches and deep penetration; a tip diameter of 1 mm to 20 mm defines the sharpness of the penetration point, directly affecting the ease of initial perforation and the level of local stress concentration; and a tail diameter of 1 mm to 50 mm matches the main body connection, determining the overall strength and stiffness of the structure. Crucially, the semi-cone angle of 15° to 45° defines the inclination of the cone surface. This angle range balances sharpness and structural strength: a smaller angle results in a sharper probe, easier to penetrate but more prone to breakage; a larger angle provides greater rigidity, with a greater lateral expansion force upon penetration. This series of optimized parameters collectively constitutes a standardized mechanical probe, making its penetration effect during impact no longer random, but quantifiable, adjustable, and reproducible. This provides a physical and geometric basis for accurately quantifying the severity of needle penetration factors and analyzing their coupling relationship with compression factors.

[0044] In one specific embodiment, the protrusion structure is as follows: Figure 4 As shown, A is the length of the raised structure, and B is the length of the bolt on the raised structure. 1 represents the tip diameter. 2 represents the tail diameter, 3 represents the bolt diameter.

[0045] S2. Obtain the voltage data, temperature data, and appearance of the battery cell, as well as the impact velocity of the impactor, during each impact test; Specifically, for the electrical and thermal state of the battery cell, a high-sampling-rate voltage sensor is directly connected to the two poles of the cell to monitor and record instantaneous changes, drops, or falls in voltage in real time. This is the most direct electrical signal to determine whether an internal short circuit has occurred. At the same time, one or more high-response temperature sensors (such as miniature thermocouples attached to key locations on the surface of the cell, or non-contact infrared thermal imagers monitoring the entire surface) are used to capture temperature changes at impact points and areas where thermal runaway may originate, recording the rate of temperature rise and peak values. The external condition of the battery cell is visually recorded using a high-speed camera device, with a frame rate sufficient to capture transient phenomena such as crack propagation, casing deformation, electrolyte leakage, smoke, or open flame.

[0046] Simultaneously, the velocity of the impactor at the moment of impact is precisely measured using techniques such as photogates, laser velocimeters, or high-speed video image analysis. This velocity value is the core input for subsequent calculations of impact kinetic energy. All these data streams (voltage, temperature, visual images, velocity) are synchronized using a unified timestamp, ensuring that every voltage drop, temperature rise, and surface crack is correlated with the precise moment of impact and the specific energy carried by the impactor. This step forms the data foundation of the entire assessment method, transforming a physical impact into a series of quantifiable and correlated digital signals, providing indispensable raw evidence for subsequent quantitative analysis and coupled assessment.

[0047] S3. Calculate the impact energy based on the mass and impact velocity of the impactor; In this step, the expression for calculating the impact energy is: E ; in, The mass of the impactor. The impact velocity of the impactor. , It is the acceleration due to gravity. The falling height or equivalent falling height of the impactor.

[0048] S4. Evaluate the safety performance of the battery cell based on voltage data, temperature data, appearance condition and impact energy under different test conditions; Specifically, the assessment uses impact energy as a unified benchmark to measure the intensity of external mechanical threats. First, under the same State of Charge (SOC) conditions (e.g., 100% fully charged), the impact energy is systematically increased for multiple tests. After each test, the corresponding voltage data (whether there is a sudden drop and its magnitude), temperature data (temperature rise rate and peak value), and physical condition (whether there is cracking or fire) are analyzed. Through this series of data, the safety threshold of the battery cell at that specific SOC can be clearly plotted, i.e., the critical impact energy that causes abnormal voltage, significant temperature rise, or physical failure. Below this threshold, the battery cell is safe; above this threshold, it enters different levels of risk or failure states.

[0049] This analysis was then repeated under different SOC conditions (e.g., 50% and 0%). Comparative analysis revealed a crucial pattern: as SOC increases (i.e., the chemical energy stored within the cell increases), the critical impact energy required to trigger the same failure mode (e.g., internal short-circuit triggering) typically decreases, while the severity of the failure (e.g., rate of temperature rise, probability of fire) intensifies. For example, a cell that can withstand a high-energy impact and only deform at 0% SOC might experience severe thermal runaway at 100% SOC with only a lower energy impact.

[0050] Ultimately, by synthesizing the data from all test conditions, the evaluation work can achieve the following: 1) quantifying and defining the specific safety boundaries of the battery cell against crush-needle-coupled damage under different internal energy states; 2) scientifically revealing the coupling and amplification relationship between internal chemical energy (SOC) and external mechanical energy (impact energy) during the triggered failure process; and 3) comprehensively evaluating the overall safety robustness of the battery cell across the entire operating range (SOC from 0% to 100%) and the range of expected threat intensity. Therefore, the evaluation conclusion in this step is no longer an isolated question of safety, but rather provides a complete and quantitative risk profile of the battery cell's safety performance as it changes with operating conditions in the complex and ever-changing real world.

[0051] S5. By using the compression assessment model and the needle puncture assessment model, the severity of the compression and needle puncture effects in the impactor are quantified respectively, in order to analyze the dominant mode in mechanical damage.

[0052] Specifically, this method delves into the microscopic analysis of damage mechanisms, moving from macroscopic observation of safety phenomena. Its key lies in the parallel application of two independently constructed, complementary quantitative models. The crush assessment model does not simply focus on the magnitude of the impact energy, but rather transforms the kinetic energy input of the impactor (typically related to mass, velocity, or height) into a standardized crush assessment factor by introducing the structural resistance parameters of the battery cell itself. This factor is essentially the ratio of the actual crush threat input to the inherent crush resistance of the battery cell, thereby accurately quantifying whether the crushing effect in this test is significantly more stringent, roughly the same, or relatively lenient compared to benchmark tests (such as static crushing in national standards), achieving an objective classification of the crush threat.

[0053] Meanwhile, the acupuncture assessment model focuses on the local invasive effect caused by the protruding structure. This model ignores overall kinetic energy and instead focuses on the geometry of the insertion and the volume of damage. It calculates the equivalent volume of damage or severity index formed by the insertion using parameters such as insertion depth and protrusion sharpness (half-cone angle), and compares this to the baseline damage of a standard acupuncture test to derive an acupuncture assessment factor. This factor clearly defines the intensity level of the insertion.

[0054] After obtaining two independent quantification factors, the analysis enters the crucial coupling resolution stage. By establishing the numerical relationship between the two factors (such as comparing their magnitudes, ratios, or constructing joint criteria), the system can scientifically identify whether overall compression deformation or local puncture intrusion played a decisive role in the final failure in this complex damage. This damage decoupling capability based on the quantification model enables this method not only to determine safety but also to reveal the physical root cause of the failure, providing direct and accurate data-driven decision-making basis for targeted safety design and protection strategies for battery cells (such as strengthening the casing or optimizing the separator).

[0055] In this step, the compression assessment model is used to calculate the compression assessment factor characterizing the severity of the compression effect, and its expression is: ; in, The total displacement caused by the work done by the impactor perpendicular to the cell surface is expressed as a function. Related to the size and mechanical properties of the battery cell, The upper limit of the displacement for work done. To test the mass of the impactor, For the quality of the battery cell under test, The falling height or equivalent falling height of the impactor.

[0056] Specifically, squeeze assessment factors Used to characterize the severity of the extrusion action, if This is more stringent than traditional extrusion testing. The stringency is consistent with traditional compression testing. This is more lenient than the traditional compression test.

[0057] In this step, the acupuncture assessment model is used to calculate the acupuncture assessment factor characterizing the severity of the acupuncture effect, and its expression is: ; in, The depth to which the protruding structure penetrates the battery cell under test. The standard insertion depth for traditional needle prick tests. It is the semi-cone angle of the convex structure.

[0058] Specifically, acupuncture assessment factors Used to characterize the severity of acupuncture effects, if 6.75 ≤ If ≤48, the stringency is the same as the traditional acupuncture test. The stringency level is higher than that of traditional acupuncture tests. The stringency of this test is less stringent than that of the traditional needle prick test.

[0059] In this step, the dominant modes of mechanical damage are analyzed, including: contrast and The value; like If so, then the acupuncture factor is determined to be the dominant mode of mechanical injury; like If the compression factor is determined to be the dominant mode of mechanical damage, then the compression factor is determined to be the dominant mode.

[0060] Specifically, after completing the squeezing assessment factor ( ) and acupuncture assessment factors ( After independent quantitative calculations, the determination of the dominant mode of mechanical damage follows a rigorous and quantifiable logical criterion. The core of this criterion is that it does not involve direct comparison. and The magnitude of their absolute values ​​is determined not by the magnitude of their product, but by analyzing their product ( ) and acupuncture assessment factors ( A comprehensive judgment is made based on the relative relationships between the two entities.

[0061] Its physical meaning lies in: product It can be considered as the overall acupuncture severity index after being corrected for the squeezing factor under the coupling effect. Specifically, if < This means dividing both sides of the inequality by a positive number. Afterwards, it is equivalent to <1. This condition indicates that, in this test, the severity of the compression effect is characterized by... The value is below the baseline for traditional compression testing (baseline is 1), meaning the compression did not pose an exceptionally severe threat. Therefore, the dominant contribution to the final damage result should be attributed primarily to the needle puncture, and the needle puncture factor should be determined as the dominant mode.

[0062] Conversely, if > Then it is equivalent to >1. This condition indicates that the severity of the compression in this test exceeded traditional test benchmarks, posing a significant and intense mechanical threat. Under these circumstances, even with the presence of a needle penetration effect, the intense overall structural compression became the more critical force driving cell failure; therefore, the compression factor was determined to be the dominant mode.

[0063] This determination method cleverly avoids the influence of... and The problem of direct comparison due to different dimensions or orders of magnitude is solved by introducing product and comparison, unifying the judgment benchmark and anchoring it to "whether the compression effect exceeds its traditional test benchmark" (i.e., The clear and objective physical nature of whether it is greater than 1. This not only makes the determination of the dominant mode scientific and unambiguous, but also directly relates to the comparison with traditional tests, providing a concise and powerful logical tool for understanding which mechanism plays a dominant role in coupling damage.

[0064] Example 2

[0065] like Figure 5 As shown, this embodiment provides a battery cell mechanical safety coupling test device, including: Impact body 1, which is provided with a structure for generating both squeezing and needle-piercing effects during impact; Fixture 3 is set on the ground 8 to fix the battery cell 4 so that the surface of the battery cell 4 faces the falling direction of the impactor 1. The release mechanism is used to release the impactor 1 so that it impacts the battery cell 4 in free fall; it consists of a rope 6, an electrically controlled hook 5, two fixed pulleys 9, and a movable gantry 2. Control module 7, located on the ground 8, is used to control the electric control hook 5 to release the impact body 1; The data acquisition unit includes a voltage sensor for acquiring voltage data of battery cell 4, a temperature sensor for acquiring temperature data of battery cell 4, a high-speed camera for acquiring the appearance status of battery cell 4, and a speed detector for acquiring the impact speed of impactor 1. The voltage sensor and temperature sensor are mounted on battery cell 4, and the high-speed camera and speed detector are located in control module 7. The analysis and processing unit (not shown in the figure) is connected to the data acquisition unit to calculate the impact energy based on the velocity data, and to evaluate the safety performance of the battery cell based on the voltage data, temperature data, appearance condition and impact energy under different test conditions; and to quantify the severity of the extrusion and puncture effects in the impactor through the extrusion evaluation model and the puncture evaluation model, respectively, in order to analyze the dominant mode in mechanical damage.

[0066] The mechanical safety coupling test of the battery cell is performed using the battery cell mechanical safety coupling test device of this embodiment, including: Multiple identical battery cells 4 are charged and discharged, so that the multiple battery cells 4 are at 0%, 50%, and 100% SOC respectively; The battery cell 4 is fixed on the fixture 3 to ensure that the position of the battery cell 4 is stable during the test. The control module 7 controls the electric control hook 5 to release the impact body 1, so that it hits the battery cell 4 in free fall, with heights of 1 meter, 3 meters and 5 meters respectively. The voltage data, temperature data, appearance status, and impact energy of cell 4 are collected by the data acquisition unit. After the impact, observe the performance of the battery cell, including whether there are any signs of cracked casing, leakage, smoke, or fire.

[0067] As shown in Table 1, with the increase of SOC, the pressure drop and temperature rise increase; with the increase of height, the pressure drop and temperature rise increase.

[0068]

[0069] Table 1. Data Recording Table of Cell Mechanical Safety Coupling Impact Tests under Different Test Conditions

[0070] Example 3

[0071] like Figure 6As shown, this embodiment provides a battery cell mechanical safety coupling test device, including: Impact body 1, which is provided with a structure for generating both squeezing and needle-piercing effects during impact; Fixture 3 is set on the ground 8 to fix the battery cell 4 so that the surface of the battery cell 4 faces the impact direction of the impactor 1. A release mechanism is used to release the impactor 1 so that it strikes the battery cell 4 in the form of a pendulum; it consists of a rope 6, an electrically controlled hook 5, and two movable gantry frames 2. Control module 7, located on the ground 8, is used to control the electric control hook 5 to release the impact body 1; The data acquisition unit includes a voltage sensor for acquiring voltage data of battery cell 4, a temperature sensor for acquiring temperature data of battery cell 4, a high-speed camera for acquiring the appearance status of battery cell 4, and a speed detector for acquiring the impact speed of impactor 1. The voltage sensor and temperature sensor are mounted on battery cell 4, and the high-speed camera and speed detector are located in control module 7. The analysis and processing unit (not shown in the figure) is connected to the data acquisition unit to calculate the impact energy based on the velocity data, and to evaluate the safety performance of the battery cell based on the voltage data, temperature data, appearance condition and impact energy under different test conditions; and to quantify the severity of the extrusion and puncture effects in the impactor through the extrusion evaluation model and the puncture evaluation model, respectively, in order to analyze the dominant mode in mechanical damage.

[0072] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for evaluating the mechanical safety coupling of a battery cell, characterized in that, include: Under different test conditions, the battery cell is subjected to impact test using an impactor, the impactor having a structure for generating both squeezing and needle-piercing effects during impact. Acquire the voltage data, temperature data, and appearance of the battery cell, as well as the impact velocity of the impactor, in each impact test; The impact energy is calculated based on the mass and impact velocity of the impactor. The safety performance of the battery cell is evaluated based on the voltage data, temperature data, appearance condition, and impact energy under different test conditions. By using compression assessment models and needle puncture assessment models, the severity of compression and needle puncture effects in the impactor are quantified respectively, in order to analyze the dominant mode in the mechanical damage.

2. The cell mechanical safety coupling assessment method according to claim 1, characterized in that, The test conditions include: The different states of charge of the battery cell, and the different impact energies obtained by adjusting the release height, release angle or mass of the impactor.

3. The cell mechanical safety coupling assessment method according to claim 1, characterized in that, The impact test is achieved by driving the impact body through free fall or a pendulum.

4. The cell mechanical safety coupling assessment method according to claim 1, characterized in that, The compression assessment model is used to calculate the compression assessment factor characterizing the severity of the compression effect, and its expression is as follows: ； in, The total displacement caused by the work done by the impactor perpendicular to the surface of the battery cell. A function related to the size and mechanical properties of the battery cell. The upper limit of the displacement for work done. To test the mass of the impactor, For the quality of the battery cell under test, The falling height or equivalent falling height of the impactor.

5. The cell mechanical safety coupling assessment method according to claim 4, characterized in that, The acupuncture assessment model is used to calculate the acupuncture assessment factor characterizing the severity of acupuncture effects, and its expression is as follows: ； in, The depth to which the protruding structure penetrates the battery cell under test. The standard insertion depth for traditional needle prick tests. It is the semi-cone angle of the convex structure.

6. The cell mechanical safety coupling assessment method according to claim 5, characterized in that, The dominant modes of analysis of mechanical damage include: contrast and The value; like If so, then the acupuncture factor is determined to be the dominant mode of mechanical injury; like If the compression factor is determined to be the dominant mode of mechanical damage, then the compression factor is determined to be the dominant mode.

7. The cell mechanical safety coupling assessment method according to claim 1, characterized in that, The impactor includes a main body and at least one protruding structure disposed on the surface of the main body.

8. The cell mechanical safety coupling assessment method according to claim 7, characterized in that, The protruding structure is a conical structure that can be detachably installed on the main body. It is made of tungsten steel or stainless steel, with a height of 5mm to 60mm, a tip diameter of 1mm to 20mm, a tail diameter of 1mm to 50mm, and a semi-cone angle of 15° to 45°.

9. The method for evaluating the mechanical safety coupling of a battery cell according to claim 1, characterized in that, The expression for calculating the impact energy is as follows: E ； in, The mass of the impactor. The impact velocity of the impactor. , It is the acceleration due to gravity. The falling height or equivalent falling height of the impactor.

10. A battery cell mechanical safety coupling test device, characterized in that, The apparatus for implementing the cell mechanical safety coupling assessment method according to any one of claims 1 to 9, the apparatus comprising: Fixtures used to secure battery cells; An impactor having a structure for generating both squeezing and needle-piercing effects during impact; A release mechanism is used to release the impactor so that it strikes the battery cell in the form of a free fall or a pendulum. The control module is used to control the release mechanism to release the impactor; The data acquisition unit is used to acquire the voltage data, temperature data, and appearance of the battery cell, as well as the impact velocity of the impactor. The analysis and processing unit is communicatively connected to the data acquisition unit. It is used to calculate the impact energy based on the velocity data, and to evaluate the safety performance of the battery cell based on the voltage data, temperature data, appearance condition and impact energy under different test conditions. It also uses the compression evaluation model and the needle penetration evaluation model to quantify the severity of the compression and needle penetration effects in the impact body, respectively, in order to analyze the dominant mode in the mechanical damage.

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